1. Field of the Invention
This invention relates generally to a power wrench, more particularly, it relates to a clutch-buffer assembly for power wrench in a low-cost simple structure to be operated easily with high efficiency and low power consumption.
2. Description of the Prior Art
In a conventional clutch device for power wrench, such as a disclosed Taiwan patent No. 109,948, the U.S. Pat. Nos. 5,740,892 and 5,412,546, the centrifugal force is applied for locking or unlocking a work piece, however, any of them is found imperfect in one way or another.
Besides, in a Taiwan patent No. 34,448, a vehicle's exhaust gas is taken as the power source in consideration of operational convenience, nonetheless, some common defects and security problems must be pondered deliberately.
Furthermore, a previously submitted application No. 089,200,156 of the present inventor sought for local patent is designed to take advantage of the vehicle's battery as power source for the sake of promoting convenience, simplifying structure, and cutting cost.
In whichever the abovesaid power wrench, the driving force directly or indirectly transmitted from a motor must exceed a least level in order to load or unload a work piece, and accordingly, a heavy-duty motor will be required for driving a relatively heavier load which seems a dilemma between the desired performance and the motor cost.